print size is not the same as the file size?

[Rod Young]

quote Paul Hodges:

In fact, if we printed the same file twice, they would be different from each other. I think it seem to affect files that have a longer linear length so it may be a proportional accumulative innacuracy?

This is the statement that sounds truly puzzling. It sounds like an issue with the media contracting/expanding due to changes in temperature. Do you use a cool room for your media? Can you comment about the temperature of your media before and after the application?

A good example concerns thermal printers, where the application heat causes the media to expand slightly. The media then cools to room temperature, causing the printed portion to appear smaller than expected.

In SignLab, the solution is to use what is called Print Stretch Correction, which involves a calculation to compensate for media shrinkage after application.

Rod at CADlink

[Paul Hodges]

cheers for that Rod,

all the media is kept in the same room as the printer, which is of average room temperature, so the media wouldn’t be coming into a different environment exactly.

I can generally compensate for it by increasing the scale on the linear length by around 5mm, but it’s not an exact science of course. The problem then, is when you have to print a design exactly edge to edge, or if you have two or three prints that have to line up or be equal.

[Tim Painter]

I know very little or make that nothing.lol

about your setup.

But what if you print say a 20mm square image & a 200mm square image. 2 different documents not on the same document.

Are they both out? or is the larger image out by a greater extent?

Just thinking aloud.

Tim.

[Paul Hodges]

Tim, I think it’s fair to say that a small document is quite accurate but if you print a document say 915mm x 915mm or bigger, you start to get that innacuracy. If the file is of a linear length of say, eight foot or more, you’re paractically guaranteed to be short of the correct length, probably by 5 or 10mm.

It’s also worth saying that it doesn’t seem to happen every time, but it is frequent.

Obviously one of the variables is causing this but i’ve yet to be able to determine which one it is.

[Tim Painter]

Have you measured the media and marked it maybe to see if it’s stretching?

Just a thought

[Paul Hodges]

Tim,

no i haven’t tried that. if it were to be the media stretching then the only soultion would be to turn off the printer heater?

in which case this must be happening on everyone else’s printers surely?

[Chris Wool]

the machine and the rip have media calibration settings and are there for you to print correctly on different thickness materials this only works over the length though the width should always be correct.
there are also several settings in the engineers mode.
with the print calibration set at 0 you should print 1 mtr length then measure and adjust the calibration to suit. that is the setting for that material only. also the rip should be set to 0 as well.

chris

[Paul Hodges]

cheers Chris, I’ll have a go with that and see what happens.

I’m pretty sure this has happened on all the different media we use.

[eddie meadows]

I had a similar problem where the machine was measuring the media incorrectly and thus printing size was also incorrect. Check that the media is being measured correctly, if not write back and I will tell you how to resolve.(I need to check back in my tech notes – I remember it involved adjusting a variable resistor to a certain tolerance.)

[Paul Hodges]

cheers eddie, i’m trying out chris’s suggestion and if that doesn’t resolve it then i’ll need to ask you how you solved that problem.

Paul

[Paul Hodges]

quote Chris Wool:

the machine and the rip have media calibration settings and are there for you to print correctly on different thickness materials this only works over the length though the width should always be correct.
there are also several settings in the engineers mode.
with the print calibration set at 0 you should print 1 mtr length then measure and adjust the calibration to suit. that is the setting for that material only. also the rip should be set to 0 as well.

chris

chris, are you talking about the feed calibration in the rip? i have looked at the media calibration settings on the printer, but the rip settings override the printer settings, you have to change that to use the actual printer settings although the feed settings in the rip come from the profile you happen to select, is that right?

Thanks

[David Rowland]

over say 2-3 mtrs we could expect the JV3 to be out about 2-3mm.. also as you print you do have control over banding (called feed compensation) which you can increase or decrease while it prints, as you do this the image does grow or shrink a slight touch.

on double sided banners the linear length can be upto 10mm out when trying to do back to back.

One thing I noted was the banner weight on the roll, a fresh heavy roll needs more effort to pull it through and a light one will fly and be more measurement correct, also take up rollers can alter the linear length as it is tugging the banner and keeping all media surfaces clean and smooth helps too.

[Paul Hodges]

cheers for that Dave,

we’ve tried a lot of different things to stop this but the results do vary, sometimes the print is dead on, sometimes it’s up to 10mm short on the length.

I have been wondering if this is just to be expected with inkjets and that maybe we’ll never be able to get it bang on all the time

I have spoken to the guys at Roland about this and their opinion is that it should always print the document size accurately.

I’ll mess with the calibration some more i think

[David Rowland]

dirty rollers? another thing. Not sure how many the roland got but JV3 has about 15 grip rollers which allows it to feed very well

[Caique Barcellos]

Take a look at your image resolution, some times I have a 300 DPIs drawn at 20×20 cm, when I put at ripper i got some like 40x40cm and when I save the same file with 150 DPIs I got the original size 20×20 cm.

Well I dont know just take a look.

[Rod Young]

quote Paul Hodges:

I’m pretty sure this has happened on all the different media we use.

I have spoken to the guys at Roland about this and their opinion is that it should always print the document size accurately.

Then would this not suggest that there is a mechanical issue with your printer? Does your SP540V Operator Manual have a list of troubleshooting issues that include this problem?

Rod

[Paul Hodges]

not anything that is exactly specific to this, no.

this is why i went direct to the technical people at Roland, because if it were a known issue, they would have probably known what to do but they weren’t aware of this happening to anyone else, nor were they aware of it being a fault with the printer.

Paul

[Shane Drew]

quote Paul Hodges:

not anything that is exactly specific to this, no.

this is why i went direct to the technical people at Roland, because if it were a known issue, they would have probably known what to do but they weren’t aware of this happening to anyone else, nor were they aware of it being a fault with the printer.

Paul

I have had this problem too Paul, mostly going from vinyl to banner printing.

Spoke to Roland here, its not a problem with the machine, as such, but because both medias have different characteristics, each media must be calibrated independantly. They tell me that banner printed on a vinyl calibration will probably print shorter, and it does. Over 4 metres on a banner print, mine comes out 40mm short than if I print the same print on vinyl with vinyl calibration.

I don’t print much banner material, so I just stretch my print 40mm longer if I am doing a 4 metre banner print again. I’m just being lazy tho, 😕

[Paul Hodges]

Shane,

I’ve ended up doing a similar thing. Even on standard vinyl printing, i usually increase the image by a tiny amount just in case it falls a little short.

Not an exact science though lol..

[David Rowland]

on the roland machines, is feedrate a profile item?

[Chris Wool]

dave
could be either in the machine menu for calibration you can say rip settings or machine settings if on machine settings the rip can not adjust the calibration.

if i print on to thin paper for working plans then the calibration is set to -.25%. this was found by printing and measuring

the thicker the material the bigger the circuference of the driving rollers so it travels further per reverloution. across the plotter no difference.

another area that alters the size is the way the softwear measures the text.
type a small line of text and set its length then convert it to curves and it will be shorter this is due to the letter control node being included in the first measurement and not in the curves if then scaling the art upwards can make a very big differance to the length expected.

chris

[Paul Hodges]

Dave,

you can adjust the feed rate i believe, both on the machine and in the rip (versaworks), just depends whether the rip settings are set to override the printer settings.
The feed rate in the rip comes from the profile so i have been loathe to change that, i think it probably influences banding too, so you could assume that the rate set in the profile for the feed must produce the least amount of banding?

sounds like chris has more or less overcome this problem with his calibration methods.
If i’m honest, our workload has been such that i haven’t actually had time to print a metre length, measure it and adjust the calibration. I’m also a little concerned about overriding the profile setting as i mentioned.

[David Rowland]

ah right… pretty similar to Paul,
Shiraz has a machine settings thing which is associated with a material profile, heat/feedrate/overprinting etc are all stored in the material profile. This can be overridden at the printer for fine tuning and adjusted before printing.

A feed rate for a heavier banner roll with possibly be more then a lighter vinyl roll and not forgetting the tug of the take up holder, all these factors influence the final measurement.

Lets say the print is 20mm out over a 2000mm print length, if I adjusted the feed rate of a typical 0.01mm this is what I would expect.

[Paul Hodges]

quote Chris Wool:

the machine and the rip have media calibration settings and are there for you to print correctly on different thickness materials this only works over the length though the width should always be correct.
there are also several settings in the engineers mode.
with the print calibration set at 0 you should print 1 mtr length then measure and adjust the calibration to suit. that is the setting for that material only. also the rip should be set to 0 as well.

chris

Chris, just saw your PM! I will give you a shout if that’s okay, if this persists. Just had an engineer visit, he couldn’t explain it except to say that maybe the heater settings were on too high, so he turned them down and we’ve yet to see if that has cured it.